Vater Resources of the Mesabi and Vermilion ron Ranges · hensive report on the Mesabi Iron Range. Grout and Broderick (1919) gave a detailed account of the Precambriaii stratigraphy

Vater Resources of the Mesabi and Vermilion ron Ranges

y R. D. COTTER, H. L. YOUNG, L. R. PETRI, and C. H. PRIOR

EOLOGICAL SURVEY WATER-SUPPLY PAPEF 1759

fhis volume was published is separate chapters A-F

UNITED STATES DEPARTMENT OF THE INTERIOR

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY

Thomas B. Nolan, Director

CONTENTS

[Letters designate the separately published chapters],

(A) Ground and surface water in the Mesabi and Vermilion Iron Range area, northeastern Minnesota.

(B) Water resources in the vicinity of municipalities on the western MesabiIron Range, northeastern Minnesota.

(O) Water resources in the vicinity of municipalities on the west-centrrl MesabiIron Range, northeastern Minnesota.

(D) Water resources in the vicinity of municipalities on the central MesabiIron Range, northeastern Minnesota.

(E) Water resources in the vicinity of municipalities on the east-centrrl MesabiIron Range, northeastern Minnesota.

(F) Water resources in the vicinity of municipalities on the eastern MesabiIron Range and the Vermilion Iron Range, northeastern Minnesota.

Ground and Surface Water in the Mesabi and Vermilion Iron Range Area Northeastern MinnesotaBy R. D. COTTER, H. L. YOUNG, L. R. PETRI, and C. H. PRIOR

WATER RESOURCES OF THE MESABI AND VERMILION IRON RANGES

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 17S9-A

Prepared in cooperation with the Minnesota Department of Iron Range Resources and Rehabilitation

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON i 1965

UNITED STATES DEPARTMENT OF THE INTERIOR

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Print'ng Office Washington, D.G. 20402

CONTENTS

PageAbstract________________________________________________________ AlIutroduction______________________________________________________ 1

Purpose of investigation______________________________________ 2History of investigation________________________________________ 2Previous investigations...._____________________________________ 2Acknowledgments- ____________________________________________ 5

Description of area________________________________________________ 5Geology_______-____--_-_--_--____----_-__-__-__-----------___ 5Definition of geologic terms____________________________________. 8Drainage..._____-__----_-_-_---_-_--__-------___-----------.- 9Climate___________-_-________--_-___________________________ 9Culture. ___________________________________ 10

Hydrology________________________________________________________ 11Hydrologic definitions..._______________________________________ 12Ground water_______________________________________________ 13

Bedrock aquifers__________________________________________ 13Drift aquifers_____________________________________________ 14

Surface water.________________________________________________ 16Low-flow frequency________________________________________ 16Floods.._________________________________ 18

Frequency curves______________________________________ 18Application of curves__________________________________ 19

Distribution of ground water and surface water by physiographicregions.________________________________________________ 21

Giants Range___________________________________________ 22Cook-Embarrass region___________________________________ 22Border Lakes region_______________________________________ 23Ice-Contact region_______________________________________ 23Glacial Lake Aitkin-Upham region__________________________ 24Morainal and Ice-Contact region.___________________________ 24Toimi drumlin field________________________________________ 25

Quality of water_______________________________________________ 25Criteria for evaluating the quality of water_______________________ 26Ground water_________________________________________________ 27Surface water,________________________________________________ 28

Present water development_________________________________________ 29Industrial use_______________________________________________ 29Municipal use_______________________________________________ 32

Considerations for future development.______________________________ 33Literature cited.________________________________.. _______________ 34

m

IV CONTENTS

ILLUSTEATIONS

PLATE 1. Map showing physiographic regions, trace of geologic section, and hydrologic features, Mesabi-Vermilion Iron Range area, northeastern Minnesota___________________________ In pocket

PageFIGURE 1. Records available for gaging stations for the period 1931-60_ _ _ _ A4

2. Geologic section through Mesabi and Vermilion Iron Rangearea.___________________________ __ ____ ______ 6

3. Schematic representation of the hydrologic cycle ____________ 114. Annual precipitation at Virginia, Minn., and discharges at

selected gaging stations.--_____________________________ 175. Annual 7-day minimum frequency curve for station 1310, Dark

River near Chisholm, Minn___________________________ 186. Composite frequency curve of annual floods within Region A,

northeastern Minnesota_______________---__-__-_-______ 197. Relation curves between mean annual flood, drainage area,

and percentage of lakes________________--_____-________ 20

TABLES

PageTABLE 1. Lithology, thickness, and water-bearing characteristics of bed

rock units__-__-___________-_____-_-_____---_--__-_____ A72. Maximum, minimum, and mean monthly temperature at

Virginia for 1931-60__________ _______________ 103. Mean monthly precipitation at Virginia for 1931-60__________ 104. Lithology, areal extent, and water-bearing characteristics of

glacial units___________________________________________ 155. Discharges, at gaging stations not materially affected by regula

tion, of annual 7-day minimums for selected recurrence intervals______________________________________________ 18

6. Flood frequency at gaging stations in and near the report area. _ 217. Chemical composition of untreated ground water used for

municipal supply (1960)________________________________ 278. Frequency distribution of chemical constituents and prop

erties of water from streams_____________________________ 30

WATER RESOURCES OF THE MESABI AND VERMILION IRON RANGES

GROUND AND SURFACE WATER IN THE MESABI AND VERMILION IRON RANGE AREA, NORTHEASTFRN

MINNESOTA

By R. D. COTTER, H. L. YOUNG, L. R. PETRI, and C. H. PRIOR

ABSTRACT

Within the Mesabi-Vermilion Iron Range area, water of good quality is avail able from the Biwabik Iron-Formation, from stratified drift, and from lakes and streams. About 700 bgy (billion gallons a year) leaves the area as surface water, of which about one-third comes from ground water.

Leached, oxidized, and fractured parts of the Biwabik Iron-Formation yield as much as 1,000 gpm (gallons per minute) to wells. Much of the permeable stratified drift within the area underlies the Ice-Contact region and the Horainal and Ice-Contact region, and several wells drilled in drift have been pumped at rates of more than 1,000 gpm.

Parts of three major drainage basins lie within the area, and lakes compose about 5 percent of the area. Low-flow and flood-frequency data have been compiled for many of the streams. Large quantities of surface water are avail able from the Border-Lakes region and the Morainal and Ice-Contact region.

The quality of ground water from the Biwabik Iron-Formation and from the drift is similar. The water is generally moderately siliceous, hard or very hard, and contains much iron and manganese. Surface water is generally soft, con tains much iron, and is highly colored.

Large uses of water in the area include: taconite processing (50 bgy), wash- ore processing (19 bgy), power plants (63 bgy), municipal water supplies (3 bgy) and paper processing (1 bgy). Optimum development of tl <j water resources might be achieved by using streamflow in the spring and stunner and ground-water and surface-water storage in the fall and winter.

INTRODUCTION

The Mesabi and Vermilion Iron Range area (pi. 1) lias a population of about 125,000, which is largely dependent on industrial employ ment. The industries and population are concentrated in two narrow bands paralleling the deposits of iron ore. The precipitation of 26 inches a year is nearly the lowest in the Eastern United States. Sur face runoff is equivalent to only about 9 inches a year, although the

Al

A2 WATER RESOURCES OF MESABI AND VERMILION IRON RANGES

numerous lakes function as reservoirs and increase the total water available during periods of low flow. The area lies on a 3-way con tinental divide, and the only surface inflow is to the extrene southwest and northeast corners (pi. 1). The remainder of the area is dependent on local precipitation.

The quantity of water available is critical to industrial expansion. Taconite processing requires about 6,000 gallons per ton of finished product; a paper mill about 40,000 gallons per ton of finished product.

Large supplies of ground and surface water of good quality are available within the report area. The major problem is economic development of these sources.

PURPOSE OF INVESTIGATION

This report describes the occurrence and quality of ^rater in the Mesabi and Vermilion Iron Range area, describes its present develop ment, and considers its potential development.

HISTORY OF INVESTIGATION

The earliest water-resources investigations in the Mess.bi and Ver milion Iron Range area were related to streamflow. The U.S. Army Corps of Engineers has recorded flow data on the Mississippi River at Grand Rapids since 1884. As early as 1911 the U.S< Geological Survey, on behalf of the U.S. Department of State, measured flows of streams tributary to or forming the international boundary water system. In 1942, five additional gaging stations were established in northeastern Minnesota in cooperation with the Minnesota Depart ment of Iron Range Resources and Rehabilitation. The Lr,ke Superior Industrial Bureau entered into a cooperative program with the U.S. Geological Survey in 1952 and furnished data for assembling a bed rock topographic map to aid in future ground-water studies on the Mesabi Iron Range. In 1953 a cooperative agreement w?\s made be tween the U.S. Geological Survey and the Minnesota Department of Iron Range Resources and Rehabilitation for an expanded study of the water resources of the Mesabi Iron Range. Work with this agency has continued to the present with only a short break during 1959. The area of study was expanded in 1959 to include the Vermilion Iron Range. This report is a result of this cooperative rtudy.

PREVIOUS INVESTIGATIONS

Because of the economic importance of the iron-bearing formations in this area, the bedrock geology has been extensively studied. Van Hise and Leith (1911) discussed all of the major iron-mining districts in the Lake Superior region. The principal reports on th?, Vermilion Iron Range are by Clements (1903) and Van Hise and Leith (1911).

GROUND AND SURFACE WATER IN MINNESOTA A3

Leith (1903, p. 29-62) summarized the early literature in a compre hensive report on the Mesabi Iron Range. Grout and Broderick (1919) gave a detailed account of the Precambriaii stratigraphy and structure of the eastern Mesabi Range. Leith, Lund, and Leith (1935) reviewed the geology of the Lake Superior region, and Gruner (1946) reported on the mineralogy and geology of the Mesabi district.. The most recent comprehensive report on this district is by White (1954). Goldich and others (1961) used radioactive age determinations to re vise the geologic column for this area.

Prior to 1932, geologists concentrated on the bedrock geology, and the principal references to glacial geology were in reports of the Minnesota Geological Survey by H. V. Winchell, Warren Upham, and U.S. Grant, and by Lawrence Martin (in Van Hise and Leith, 1911, p. 427-459). The only major work on the Pleistocene geology of the area is by Leverett (1932). Wright (1955,1956) made some modifica tions of Leverett's interpretations. A map showing geomorphology and surficial geology (Cotter and others, 1964) covers the two iron ranges.

The water resources of the area have been described only briefly. Thiel (1947) summarized the geology and ground-water conditions in northeastern Minnesota. A report on test drilling in the Mountain Iron-Virginia area (Cotter and Rogers, 1961) and a mimeographed basic-data report on municipal water supplies (Cotter and Young, 1960) refer specifically to the Mesabi and Vermilion Iron Ranges.

Minnesota Department of Conservation, Division of Water's Bul letin 5 (1951), tabulated all available flow records of streamr in the Mesabi Range. Through the 1960 water year, basic data for gaging stations were published by the Geological Survey in an annual series of water-supply papers, "Surface Water Supply of the United States." Records for this area are found in part 4, St. Lr.wrence River basin, and part 5, Hudson Bay and Upper Mississippi River basins. The latest of this series are Water-Supply Papers 1707 (U.S. Geol. Survey, 1961) and 1708 (U.S. Geol. Survey, 1962a). Beginning with the 1961 water year, streamflow records and related data are published by the Geological Survey in annual reports by State. "Sur face Water Records of Minnesota, 1961" (U.S. Geol. Survey, 1962b) contains the latest published data for this area. The bar chp.rt (fig. 1) shows periods of gaging-station records used in this report. Rec ords from stations affected by extensive artificial regulation are not included.

Records of the chemical quality of surface waters in the are?, of this report are published annually in the series of water-supply papers entitled "Quality of Surface Waters in the United States," parts 4

A4 WATER RESOURCES OF MESABI AND VERMILION IEON RANGES

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and 5. Lohr and Love (1954, p. 230, 239) listed chemical analyses of the Hibbing and Virginia municipal supplies.

ACKNOWLEDGMENTS

Municipal officials furnished data on water supplies near nunici- palities. Mining companies operating in the area furnished1 maps and well records and allowed examination of mine faces.

DESCRIPTION OF AREA

The area of this report is shown on plate 1. Most of its 5,000 square miles lie in Itasca and St. Louis Counties, and it includes the economi cally important parts of the Mesabi and Vermilion Iron Ranges.

White (1954, p. 1) designated the Mesabi Eange as " * * * the preglacial outcrop area * * * of the Biwabik iron-bearing forma tion * * * ." As used in this report the Mesabi Range referr to the area of economic importance along the Biwabik suboutcrop rud in cludes the municipalities whose economy is at least partly dej undent on the iron resources. The Mesabi Kange is about 90 miles in length and extends from Grand Rapids which is shown in the southwest part of plate 1 to Babbitt in the northeast.

The Vermilion Iron Range was described by Clements (1903, p. 32) as having an area of approximately 1,000 square miles within " * * * a narrow belt extending east-northeast from near tl ^ west end of Vermilion Lake * * * to the vicinity of Gunflint Lake, on the international boundary * * *." For the purposes of this report, it is restricted to the area of present economic importance near Tower- Soudan and Ely.

GEOLOGY

Geology controls the water resources in the area. The shape of the land surface and the character of the rocks determine stream patterns, the position of lakes, and the occurrence of ground water. The quality of water is affected by soluble rock materials with which the water comes in contact.

The rocks of the Mesabi-Vermilion Range area are of two basic types: bedrock and unconsolidated glacial drift. The bedrock is predominantly Precambrian basement rock but includes some Cretace ous sedimentary rocks. Pleistocene drift overlies the bedrock and forms the land surface.

For a description of the Precambrian basement rocks the reader is referred to those publications cited under "Previous investigations" and specifically to Goldich (1961), Schwartz (1956), and White (1954). The general relations of these rocks are shown in figure 2.

772-275 65 2

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TABLE 1. Lithology, thickness, and water-bearing characteristics of bedrock units

Formation or group

Coleraine For mation of Stauffer (1933)

Duluth Gabbro Complex

Virginia Argillite

Biwabik Iron- Formation

Pokegama Quartzite

Giants Range Granite

Vermilion Granite

Knife Lake Group

Soudan Iron- Formation

Ely Greenstone

Maximum thick ness (feet)

50

(?)

2,000

800

350

(?)

(?)

22, 000

Hundreds

Thousands

General lithology

Basal conglomer ate, sandstone, siltstone and shale.

Coarse-grained olivine gabbro.

Thinly bedded gray to black argillite.

Taconite dark- colored hard dense iron-bear ing silicic rock.

Ore black, yel low, or red, soft iron-bearing porous rock.

Varicolored vitre ous quartzite.

Hornblende gran ite and biotite granite.

Granites and gneissic rocks.

21 members in cluding: slates, graywackes, tuffs, conglom erates, and breccias.

Dark-colored dense iron-bear ing rocks.

Schist, altered ba saltic lavas, and elastics.

Water-bearing characteristics

Is not known to yield water to wells in the area.

May yield 5-15 gpm from fractured zones near its upper surfaces.

Yields up to 30 gpm from fractured zones near its upper surface. Uti lized for numerous domestic supplies and for Iron Junction municipal supply.

Yields up to 1,000 gpm to wells in highly frac tured taconite and ore. Utilized for numerous municipal and ir dustrial supplies. See text.

May yield 5-15 gpm from fractured zones near its upper surface. A well at the former commu nity of Mahonin«;report- edly obtained 80 gpm from this formation.

Yields 5-15 gpm from frac tured zones near its upper surface.

May yield 5-15 gpm from fractured zones near its upper surface.


Conglomerate, sandstone, and shale exposed in the open-pit mines on the Mesabi Iron Range have been identified as Cretaceous by their fossil content (Bergquist, 1944, p. 2).

During the last million years the Mesabi and Vermilion Iron Ranges were overridden by many Pleistocene continental glaciers. These massive ice bodies incorporated rock fragments from, and deposited sediments on, the terrain over which they passed. Th^ sediments deposited by the glaciers may be made up of locally derived material or of material from an area much farther north, toward the source of the glacier. In the Mesabi and Vermilion Iron Range area, glacial deposits cover most of the underlying bedrock. Bedroclr is exposed along the Giants Range and the Vermilion Iron Range and locally in the intermediate area.

The glacial deposits that occur within the area of thir report are tabulated on table 1. Although their color, lithology, and known areal extent are given in this table, their detailed stratigraphy is not discussed. The reader is referred to the section on "Prevrous investi gations" for a list of reports dealing with the stratigraphy of some of these units. For principles of glacial geology, see tex^ by Flint (1957) andThwaites (1950).

DEFINITION OP GEOLOGIC TERMS

The following geologic terms are used in discussions of ground- water sources and are defined as follows to aid in understanding ground-water availability.

Drift. All deposits resulting from glacial activity.Drumlin. A linear teardrop-shaped hill that is formed either by

erosion of the country rock and (or) older surficial drift, or bydeposition of till.

End moraine. A ridgelike deposit formed at the glacier front whenthe ice front is stationary.

Esker. A sinuous generally discontinuous ridge of washed sedimentsdeposited by melt-water streams flowing on, in, or under theglacier.

Glacial lake. A lake formed by blocking of drainage by ice. Ice-contact stratified drift. Stratified drift deposited by melt water

adjacent to the ice. Ice-contact topography. Irregular terrain characterized by kettles,

eskers, and kames.Kame. A mound of poorly sorted ice-contact stratified drift depos

ited as a fan or delta against the edge of the ice, or as a fillingin an opening in the ice.


Kettle. A depression in drift, made by the wasting away of a de tached mass of glacier ice that had been either wholly or partly buried in the drift.

Outwash. Stratified drift deposited beyond the ice front by melt- water streams.

Pitted outwash plain. A plain composed of outwash and charac terized by kettles.

Stratified drift. Sorted and layered drift, deposited from glacial melt water.

Suboutcrop. What would be the outcrop if the overlying uncon- formable formation were removed.

Till. An unsorted mass of rock fragments ranging in size frcm clay to boulders deposited directly by the ice.

DBAINAGE

Parts of three major drainage basins are shown on plate 1. The Laurentian Divide, following in part the crest of the Giants Eange, separates waters flowing north to Hudson Bay from those flowing south to the Mississippi River and Lake Superior. A divide that ex tends south of the Laurentian Divide from a point north of Fibbing separates the southward-flowing waters into those flowing southwest to the Mississippi River and the Gulf of Mexico and those flowing south east to Lake Superior and the St. Lawrence River. The main streams in the Hudson Bay basin are the Basswood, Vermilion, and Little Fork Rivers and their tributaries; in the St. Lawrence River basin, the St. Louis River and its tributaries; and in the Mississippi River basin, the Mississippi River and its tributaries.

CLIMATE

"Owing to its midcontinental location, Minnesota has a marked continental climate, characterized by wide variations in temperature, scanty winter precipitation, normally ample summer rainfall, and a general tendency towards extremes in all climatic features" (U.S. Dept. Agriculture, 1941, p. 933). The area shown on plate 1 is in the northeast and north-central divisions of the State as established by the U.S. Weather Bureau. Averaging the long-term means cf these two divisions gives a mean spring and summer (April-September) temperature of 56.8°F, and a mean fall and winter (October-1 larch) temperature of 21.6°F. The mean temperature for January is 8.4°F and for July is 57.0°F. The average growing season is 90-110 days; the average date of the first fall frost is September 9. The following table shows the temperature ranges at the Virginia meteorological station.


TABLE 2. Maximum, minimum, and mean monthly temperatures at Virginia,for 1931-60

Month

January __ ___ _ ____ ______________February _ ___ __ ________ _____ ___March _ ____-_. ___ _ __ ____ _____ ___

IVTn vJune_ ____ ___ _ __ ____ _ _ ______ _July---- - -___ --_-____ _-_---_

September... _ _ _ _ __________ _____ __October ___________ _ ___ ___________ _November __ ___ _ _ ______ _ ______December.- _ ____ ________ __________

Maximum

5353819196

1021039799886854

Minimum

-42-41-29-0?

1?2736312101

-If-41

Mean

8. 311. 923. 539. 953. 062.568. 165. 455. 744. 926. 813. 1

The average annual precipitation, based on averaging tin long-term means of the two divisions, is 25.92 inches. The spring and summer average is 19.05 inches, and the fall and winter average is 6.87 inches. During the growing season, most of the precipitation occurs in the form of thunderstorms. Table 3 shows average monthly precipitation at Virginia.

TABLE 3. Mean monthly precipitation, in inches, at Virginia for 1931 60

January ___ February__ March. _._ April. _-__ May____ June______July August. _ _ September. October. __ November. December.

1. 00 .75

1. 402. 142. 853. 793. 633. 763. 092. 051.74

. 93

CULTURE

The economy of the iron range area is largely determined by activity of the mining industry, which employs or is served by a large percent age of the population. The population of the area shown on plate 1 is estimated to be 126,000, of which about 84,000 are concentrated in municipalities.

The tourist industry is of major importance in the northeastern part of the State, where many lakes make the area particularly popular for recreation.

Farming is a minor part of the economy. In 1954, one-third of the 5,269 farms in Itasca and St. Louis Counties were dairy farms and more than half the value of products sold was in dairy products (U.S. Bureau Census, 1956, p. 60-68). More than half of the farm operators in Itasca and St. Louis Counties had other income exceeding the value of farm products sold.

GROUND AND SURFACE WATER IN MINNESOTA All

Other industries in the area include a paper company in Grand Rapids, wood-processing plants in Grand Rapids and Virginia, public utility powerplants in Cohasset and Hoyt Lakes, sand and gravel operations, and logging operations.

HYDROLOGY

The hydrologic cycle (fig. 3) shows the movement of water from the time it falls as precipitation until its return to the atmosphere. Water is constantly in motion, whether it is ground water, whose rate of movement may be in the order of inches per year through openings in. rock, or whether it is surface water flowing in streams, whose rate of movement is measured in feet per second. Water for man's use is commonly obtained from lakes or streams (surface water) or from permeable earth materials that yield water to wells and springs (ground water).

Precipitation (snow and rain)

FIGURE 3. Schematic representation of the hydrologic cycle.


HYDROLOGIC DEFINITIONS

The following terms are used in this report in describing the occur rence of water.Aquifer. A formation, group of formations, or part of r, formation

that yields water.Artesian aquifer. (An aquifer overlain by a confining b^d of lower

permeability. Water in the aquifer is under sufficient pressure to rise above the base of the confining bed in a well.

Base flow. That part of streamflow composed largely of ground- water effluent.

Discharge, ground-water. Eelease of ground water to tro land sur face, a surface-water body, or the atmosphere.

Discharge, surface-water. Streamflow measured in cubic feet per second.

Drainage basin. A surface area occupied by a surface stream or body of impounded surface water together with all tributary sur face streams and bodies of impounded surface water.

Drainage divide. The rim of a drainage basin.Gaging station. A particular site on a stream where systematic ob

servations of discharge are obtained.Ground water. That part of the subsurface water that is in the

zone of saturation.Mean annual flood. The average of the maximum flocds of each

year of record.Permeability. The capacity of a material to transmit water.Porosity. The ratio of the total volume of interstices in a material

to its mass.Recharge, ground-water. Addition of water to an aquifer by infil

tration of precipitation through the soil, by flow from streams or other bodies of surface water, or by flow of ground yater from another aquifer.

Recharge area. An area where water is absorbed which eventually reaches the zone of saturation.

Recurrence interval. The average period of time within which a flood or low flow of specific quantity will occur.

Regulation. The artificial manipulation of the flow of r, stream.Runoff. That part of precipitation that appears in surface streams.Static water level. The level to which water will rise in a well under

its full pressure head.Surface water. Water on the surface of the earth.Water table. The upper surface of a zone of saturation except where

that surface is formed by an impermeable body, in which case no water table exists.


Zone of saturation. Zone below the ground surface whose rock in terstices are filled with water under atmospheric, or greater, pressure.

GROUND WATER

Ground water occurs in primary pore spaces in unconsolidated and consolidated rocks and in secondary solution and fracture openings in consolidated rocks. Porosity controls the quantity of water that can be held in an aquifer and permeability controls the rate c f yield to wells. For a comprehensive discussion of the principles of occur rence of ground water, the reader is referred to Ferris and others (1962) andMeinzer (1923aandb).

Two rock types in the Mesabi-Vermilion Iron Range area are known to yield large quantities of water to wells. They are the permeable altered parts of the Biwabik Iron-Formation and the stratified de posits of the glacial drift. Most of the wells completed in the E iwabik are artesian; glacial drift wells may be either artesian or water table.

BEDROCK AQUIFERS

Except for the altered parts of the Biwabik Iron-Formation, the bedrock in the report area yields little water to wells (table 1).

The Biwabik Iron-Formation is divided into four members. They are, from oldest to youngest: lower cherty member, lower slaty member, upper cherty member, and upper slaty member. Following common usage (Gruner, 1946, p. 5), all rocks in this formation except the ores proper are called taconite in this report. The altered zones where the taconite has been oxidized, hydrated, and leached are mainly in areas where the taconite was previously broken by folding and faulting, thus exposing it to these processes.

As described by Gruner (1946, p. 94-102), the end product of these processes depends upon the processes involved and the type of taconite altered. The slaty taconites found mainly in the upper and lower slaty members commonly alter to "paint rock," a sticky, clayey rock of low permeability. The cherty members may alter to a more permeable rock.

The following description of textures is adapted from Gruner (1946, p. 101-102). Oxidation and hydration of taconite minerals Y°ith no subsequent leaching, produces a "* * * highly fractured, crimbly, almost silt-like material in some parts of the taconite, and porous though cemented layers in others." Where extensive leaching has taken place, porosity may exceed 50 percent. Following the collapse of the rock due to the large percentage of void space, porosity of as high as 40 percent may remain. "Even pieces which look relatively

772-275 65 3


massive and solid, almost like the original oxide bands of unaltered taconite are full of minute pores."

Oxidation of the taconite on the west end of the Mesabi Range is extensive, but leaching is incomplete (White, 1954, p. 81). Although this has resulted in a lower grade ore or a noncommercial deposit, it has increased the permeability of the formation. White (1954, p. 81) described the altered cherty members of the western Mesabi Range as consisting mainly of "* * * goethite-martite bands alternating with partly decomposed, friable, powdery chert bands."

On the central and eastern Mesabi Range, oxidation is less wide spread, but leaching is more complete where oxidation has taken place (F. L. Klinger, oral commun.).

The Biwabik Iron-Formation has been test drilled extensively for mining exploration, but, except for the present municipal wells, few water-well test holes have been drilled. Pumpage data from these wells indicate that locally the formation is highly permeable. Wells drilled in the vicinity of mines may penetrate permeable horizons. If an ore body is not completely mined out, wells adjacent to the pit may penetrate permeable water-bearing ore. Locally, the iron formation may be an aquifer beyond the limits of the ore body proper. The transition between an ore body and the surrounding taconite may be a marginal mass of oxidized but poorly leached taconite (Gruner, 1956, p. 207) or it may change abruptly from unaltered taconite to an oxidized and highly leached ore body (Gruner 1956, p. £10).

The yield of wells in the Biwabik Iron-Formation is limited by the available recharge. Over much of the Mesabi Range the Biwabik laps against the south flank of the Giants Range, and the recharge area is limited to that zone south of the crest of the Giants Range and north of the southern limit of the Biwabik suhoutcrop. Further, where open-pit mines have been drained, the water level in the vicinity of the mines is lowered and wells finished in the Biwabik must obtain water from a level lower than the dewatered zone. Where mining has stopped, many of the pits have filled with water. Wells drilled in permeable sections adjacent to the water-filled pits would induce re charge from the pits.

DRIFT AQUIFERS

The best aquifer in the drift is coarse stratified sand and gravel (table 4). It is widespread and generally highly permeable. The size, shape, and permeability of the stratified drift bodies differ greatly depending on the conditions of deposition. Some have a distinct topographic expression, whereas others have none and must be located by test drilling.


TABLE 4. Litliology, areal extent, and, wafer-bearing characteristics cf glacial,un its

Drift type

Till.. ...

Stratified drift

Lithology

to brownish-gray.

Till, clayey, silty, brown to gray, calcareous.

Till, sandy, gravellybouldery, gray to brown.

Till, sandy, clayey, silty, brown to brownish-red.

Till, clayey, silty, sandy, yellowish-brown to gray.

medium- to dark-gray, calcareous.

Clay, silty to sandy clay..--

Sand and gravel; silty sandand gravel

Known areal distribution within the area of this report

between Kelly Lake and Hoyt Lakes.

Western half of figure; as far east as Tower north of the Giants Kange.

South of Giants Range west of Kinney.

South of Giants Range west of Hibbing.

Discontinuous throughout entire area.

. .do... _. _-_ ..do.. .

..do.

Water-bearing characteristics

to wells in the area; may furnish recharge to wells in adjacent mor^ per meable drift.

Do.

wells. Is not known to yield water

to wells in the area; may furnish recharge to wells in adjacent, more per meable drift.

Do.

Do.

Do.

Do.

hundred gpm to wells.

to wells; well 6F 18.12ccc3, near Virginia was pumped at 2,000 gpm.

On the Vermilion Iron Range, glacial deposits are thin or absent, and the principal aquifers are coarse outwash deposits in narrow glacial drainageways. Isolated kames are potential aquifers, bit they are topographic highs underlain by bedrock and, consequently, have slight saturated thickness.

On the Mesabi Iron Range the drift thickens south from the Giants Range. From Chisholm east, most of the stratified drift is of ice- contact origin and lies beneath a surficial reddish-brown clayey till and above a gray bouldery till. West of Hibbing the drift is thicker, and stratified drift is common above and below the gray bouldery till.

In the vicinity of municipalities where considerable test drilling has been done, more is known about the distribution of the glacirl units. Although the tills are not assigned ages in this report, they have been grouped into units on the basis of their lithology. Table 3 gives the areal distribution and water-bearing characteristics of glacial units within the report area.

The maximum yield available from a stratified drift aquifer is prin cipally dependent on the permeability and saturated tMcknes' of the stratified drift and of adjacent sediments, and on proximity to drain age divides, open-pit mines, and surface-water bodies.


SURFACE WATER

Surface water is that part of precipitation that is observed as lakes or streams. It is the part remaining after ground percolation, evap oration, and transpiration have occurred. The part of streamflow that is the result of ground-water movement into the channel is the base flow.

Surface-water flow, being mostly from overland runoff, is subject to wide variations in volume owing to seasonal changes and to storm runoff. Figure 4 shows the annual precipitation at Virginia and the discharge per square mile at four gaging stations in the area. Some of the indicated variations between rainfall and runoff are due to the Virginia rainfall station not being representative of the whole area.

LOW-FLOW FREQUENCY

For any water supply the question of adequacy is the first to be considered. Will there be enough to meet the minimum requirement ? Will the deficient periods, if any, be of such short duratkn that they may be neglected? Will the intervals between periods of low flow be great enough to warrant the development of the supply ?

To obtain at least partial answers to these questions, low-flow fre quency studies based on the annual 7-day minimum discharges were made, and curves were developed for 19 gaging stations unaffected by regulation. The period of record used was the standard 1931-60 period, and the climatic year April 1 to March 31 was used as the basis for the annual computations. Records for gaging stations in the area did not cover this entire period, and it was necessary to make extensions by correlation with long-term records of nearby stations. The best correlation was obtained with the Little Fork, Big Fork, Baptism, and Basswood Rivers, and the records were extended by averaging combinations of records from these streams. A typical frequency curve for the annual 7-day minimum flows is that for the Dark River near Chisholm (fig. 5). Table 5 lists the data for all the stations. The recurrences were determined for intervals as great as the curve definition would allow. This meant that some were deter mined for the 30-year intervals and others for shorter intervals.

For those not familiar with the use of frequency curves, whether for floods or low flows, it should be emphasized that frequenc7 curves are not exact determinations of a fixed time interval; a 10-yoar flood or low flow will not occur once each 10 years. A 10-year flow means that a discharge of this magnitude will recur about 100 timer each 1,000 years.

1931

&

1935

DIS

CH

AR

GE

, IN

C

UB

IC

FEET

P

ER

S

EC

ON

D

PER

S

QU

AR

E

MIL

EA

NN

UA

L P

RE

CIP

ITA

TIO

N,

IN

INC

HE

S

s

1940

1945

1950

1955

1960


z o oW 12.0 a: 10 0LU

°- 8.0

uj 6.0^ 5.0 Om 4.0D

DISCHARGE, IN 1-1 ro c !-"b be

\^^

»^ p̂ ^^« ^ 4 -~e »̂~***Q»

^*^~-*

^^\"~~~~~ ~^~. ~~» -~-~ -^ ~~~^

~~~-^ . »

01 1.1 1.3 1.5 2 34568 10 20 30 4

RECURRENCE INTERVAL, IN YEARS

FIGURE 5. Annual 7-day minimum frequency curve for station 1310, Dark River nearChlsholm, Minn.

TAB:LE 5. Discharges at gaging stations not materially affected ~by regulation of annual 7-day minimums for selected recurrence intervals

Station

1245 1250 1255 1260 _1265 _ _

1275- -_1285 1290

1305 1310

1315 1320. _2170 145 170

180. 190 ___195 200

Station name

Vermilion River below Vermilion Lake near Tower.

Dark River near Chisholm __ _ _ _

Little Fork River at Little Fork.. .... Big Fork River at Big Falls __ _. _

Baptism River near Beaver Bay ___

Embarrass River near McKinley __ West Two River near Iron Junction ...

Drainage area

(sq mi)

341

180 53.0 68.5

1,740 115 483

187 50.6

1,730 1,460

254 140 93.8

17168.4

112 254

Runoff for 2-year re currence interval

(cfs per sq mi)

0.158

.094

.043

.058

.218

.049

.166

.053

.089

.039

.048

.157

.079

.034

.117

.083

.161

.114

Discharge, In cfs, for recurrence Intervals, In years shown

2 years

54 110 17 2.3 4.0

380 5.6

80

10 4.5

67 70 40 11 3.2

20 5.7

18 29

10 years

29 68 9.0 1.1 1.2

192 2.9

20

5.2 2.2

3725 25 2.7 1.4

12 2.7

11 13

20 years

346.7 .8 .7

130

9.6

4.2 1.9

3120

1.4 1.1

30 years

30 5.7 .7 .5

96

6.0

1.7

27 18

.9

FLOODS

FREQUENCY CURVES

In order to determine the frequency and magnitude of flooding that might be expected in a given area, curves can be constructed using the methods described by Dalrymple (1960). A frequency curve for northeastern Minnesota (region A of Prior and Hess, 1961, pi. 1), shows the relation between recurrence interval and ratio of a probable flood to the mean annual flood for the report area (fig. 6). Curves also show the relation between mean annual floods, drainage area, and percentage of lake area (fig. 7).


O3u_ _J on

ANNUAi c

Z < Ld2

O i n

O

5 cc

0

_

^--^

^

^^ ff

£

f>^/

1.01 1.10 1.50 2 3 4 5 6 8 10

RECURRENCE INTERVAL, IN YEARS

20 30 40 50

FIGUBB 6. Composite frequency curve of annual floods within region A, northeasternMinnesota.

APPLICATION OF CURVES

From the preceding curves, the recurrence interval of a flood of any magnitude can be approximated if the drainage area and percentage of lake area are known.

If, for example, a site on a stream having a drainage are 11 , of 200 square miles is under consideration, and an investigation indicates that 3 percent of this area is covered by lakes, the mean annual flood can be determined from figure 7 as 1,500 cfs (cubic feet per second).

To determine the recurrence interval of a flood of 3,000 cfs, the ratio is obtained by dividing this value by 1,500 cfs which equals 2.00. Using figure 6 and entering the curve at 2.00, it is found that the curve is intercepted at a recurrence interval of about 21 years.

Table 6 gives the values of the 10, 20, and 30 year floods computed on the basis of figures 6 and 1. The 30-year values are obtained from an extension of the ratio-recurrence curve and are therefore cf a more speculative nature than are the 10- and 20-year values.

In order to compare the yield during periods of low flow of the various drainage basins in the area, the runoff per square mile for the annual V-day minimums that have a recurrence interval of 2 years was computed for the gaging stations not affected by extensive regulations.

There is no definite pattern related to the geographic location of the drainage areas. The most dominant factor seems to be the per-


centage of lake area in the basins, as the natural storage therein tends to sustain the yield during periods of deficient precipitation.

The data and interpretations regarding surface water will aid those planning utilization of available water and planning installations that need protection from flooding by eliminating some of the un knowns always present in ungaged areas. A knowledge of deficient flow will indicate the necessity of utilizing storage to bridge the low periods; or such knowledge might reveal a site to be impractical.

30,000

10,000

5000

1000

10030 50 100 500 1000

DRAINAGE AREA, IN SQUARE MILES5000

FIGURE 7. Eelation curves between mean annual flood, drainage area, and percentage oflakes.


TABLE 6. Flood frequency at gaging stations in and near the area of this report

Station

1260-.. 1265... _ .

1285...-

1305 _ . _

1315.......

1320...- _

145...- _ -155. 160....

165 ___ -170.... 180... 190....

200........

Station name

Vermilion River below Vermilion Lake near Tower.

Drainage area

(sqmi)

341180 53.0 68.5

1,740

115 483 187 50.6

1,730

1,460 254 140 26.3

156

312 93.8

171 68.4

112 254

Flood, in cfs, for recurrence interval, in years, shown

10 years

3,470 1,790

694 384

8,900

1,630 1,900 1,810

592 17,300

11,600 480

4,830 48

2,050

2,700 1,150 1,570 1,060 2,140 3,680

20 years

4.23C 2,180

84C 46f

10, SOP

1,990 2,320 2,200

21, 100

14,200 585

5,890 58

2,500

3,300 1,400 1,910 1,290 2,610 4,480

30 years

4,990 2,580

998 552

12,800

2,350 2,740 2,600

851 24, 800

16,700 690

6,950 69

2,940

3,890 1,650 2,260 1,520 3,080 5,290

A consideration of the number of high flows that may be expected can be balanced against the economic considerations of how far the design should go in preventing flooding. A typical example is the question of whether to build a highway fill with bypass structures so as to withstand all flooding, or to build at much less cost with the expectation of loss at predetermined average intervals.

DISTRIBUTION OF GROUND WATER AND SURFACE WATER BY PHYSIOGRAPHIC REGIONS

The distribution of water resources within the area of thi? report is discussed by physiographic region (pi. 1). Each region has a unique physiography that broadly determines water occurrence. Th°i names of the regions as used in this report are generally as Wright (1956, p. 10-15) designated them, but some are extended and slightly modified, and two additional regions (Morainal and Ice-Contact region and Ice-Contact region) are added.

Physiography relates landforms to geology. The composition, mode of deposition, and extent of weathering of the rocks control the shape of the land surface. This shape controls the pattern of surface-water flow and the distribution of lakes.

Individual rock types can be inferred from their characteristic landforms. Both near-surface ice-contact deposits and outwasr plains, which are major aquifers in the area, can be identified by their charac teristic topography. These and other glacial landforms h&,ve been delineated on a glacial map that covers most of the area of this report. (Cotter, Young, and Winter, 1964.)


GIANTS RANGE

The most prominent topographic feature in the area of this report is the Giants Range, a long ridge trending northeast parallel to the Mesabi Iron Eange (pi. 1). At the longitude of Virginia and Eveleth the ridge is Z shaped. This flexure is known as the Virginia Horn.

The Giants Eange generally stands 100-480 feet above the sur rounding land surface and is highest on the east and central Mesabi Eange. Toward the west the Giants Eange decreases in altitude and merges into the surrounding land surface. It reaches a maximum altitude of about 1,950 feet above mean sea level at P:ke Mountain, north of McKinley. North of Coleraine its altitude is 1,560 feet. West of Coleraine it is not a discernible topographic feature, and its trend is obscured by transverse glacial landforms.

Except for a few very small streams and the southward-flowing Embarrass Eiver, whose drainage basin extends 25 miles north of the Giants Eange, the crest of this ridge forms the drainage divide for waters flowing north and south. This region contains only a few small lakes and streamflows are very low. Its surface-water potential is poor.

The Giants Eange is formed by the southernmost exposures of the Giants Eange Granite. The drift cover is very thin or absent, and the only stratified drift is in the form of boulder pavements restricted to notches in the crest. Neither the drift nor the bedrock is a reliable source of water and the ground-water potential is poor.

COOK-EMBARRASS REGION

The Cook-Embarrass region lies between the Giants Eange and the Vermilion moraine (pi. 1). From the south shore of Birch Lake past the south shore of Lake Vermilion, the moraine is the north limit of the region and is discernible on plate 1 as a line of discontinuous ridges. Although the region is largely low and swampy, it is crossed by two east-west morainal ridges. The underlying bedrock surface is very irregular and crops out in many parts of this region. Glacial drift has filled bedrock lows lessening irregularity of ttn terrane.

Drainage is sluggish, and swamps are large. The major streams draining the region include the Dark, Embarrass, Little Fork, Pike, Prairie, and Sturgeon Eivers. Several lakes are associated with the moraines. Surface-water potential of the region is fair.

The stratified drift includes lake sediments, spotty occurrences of ice-contact drift, and scarce occurrences of outwash. Babbitt obtains its water supply from a pitted outwash plain, Chisholm from buried outwash, and Tower-Soudan from a narrow channel fill. Ground-


water potential of the region is fair, but locally it is good in areas of outwash and ice-contact drift.

BORDER-LAKES REGION

The border-lakes region is north of the Vermilion Moraine and contains the Vermilion Iron Eange (pi. 1). The region consists of low irregularly shaped bedrock hills and ridges separated by numerous lakes. The drift cover is thin or absent in this area, and the topography is controlled by the underlying bedrock. The east-northeast trend of the bedrock structure is reflected by the shape of the lakes and the stream patterns.

The region contains several large lakes including Birch, Burntside, Trout, Vermilion, and White Iron, and the Kawishiwi, Stony, g.nd Ver milion Eivers. Ely obtains its water supply from Burntsic1 ^ Lake. The surface-water potential is very good.

Some stratified drift occurs in the region as thin isolated ice-contact deposits and outwash in narrow glacial drainageways. Although the ground-water potential is fair in these deposits, the potential of the region, as a whole, is poor.

ICE-CONTACT REGION

The Ice-Contact region parallels the central southern flank of the Giants Eange. It is a belt of irregular glacial topography that averages about 5 miles in width (pi. 1). Eskers, kettles, and kames are common, and many of the kettle holes are occupied by lakes. Be cause of these diagnostic landforms, the deposits within this area are referred to as ice contact. However, the sediments are, in p^rt, outwash deposited by melt-water drainage through notches in th°- Giants Eange. East and West Two Eivers, East Swan Eiver, and numerous other small streams head in the Giants Eange immediately north of the region and have relatively low flows. The Embarrass and Partridge Eivers have large drainage areas and greater flows. Large lakes in the region are Embarrass, Whitewater, Colby, Ely, and St. Marys of which the latter three are the respective water supplies for Hoyt Lakes, Gilbert, and Eveleth. Surface-water potential is fair.

The Biwabik Iron-Formation underlies the northern part of the region and is locally an important aquifer. Biwabik, Buhl, and McKinley obtain their water from this formation.

Stratified drift is widespread throughout the region but thins near the Giants Eange. Test drilling and test pumping have shown this drift will yield large quantities of ground water. Mountain Iron and Kinney obtain their water supplies from drift, and Aurora, Hibbing, and Virginia from both drift and the Biwabik. The ground-water potential of the region is very good.


GLACIAL I,AKE AITKIN-TJPHAM REGION

Southwest of the Ice-Contact region is the Glacial Lake Aitkin- Upham region (pi. 1), a low flat-lying area, formerly occupied by gla cial Lakes Aitkin and Upham. Surficial deposits of peat, clay, silt, and sand obscure the shape of the underlying drift surface. Within the northeastern part of the lake basin, numerous "islands" of ice- contact stratified drift are exposed above the level of the surrounding lake sediments.

Drainage is sluggish and most of the region is covered by swamp. A few lakes are associated with ice-contact deposits near the margin of the region, and the Mississippi and St. Louis Rivers and their tribu taries flow southward through the region. The surface-water poten tial is good for the areas near rivers, but only fair for the region as a whole.

The ground-water potential for the stratified drift in the north eastern part of the region is good. The remainder of the region is probably underlain by fine-grained lake sediments and till, and the potential for the region as a whole is poor.

MORAINALi ANI> ICE-CONTACT REGION

The Morainal and Ice-Contact region is west of the Glacial Lake Aitkin-Upham region and extends north across the Giants Range (pi. 1). It is an area of very irregular hummocky glacirl topography containing numerous lakes. The principal "grain" of the land sur face, as shown by the lakes, ridges, and eskers, is south-southeast, but some smaller features trend southwest or west. The region is a morainal complex containing associated ice-contact deposits.

The Big Fork and Little Fork Rivers drain the region north of the Laurention Divide. The Mississippi and its tributary the Prairie River drain the region south of the divide. There are numerous large lakes within the region, the largest being Pokegama Lake. The sur face-water potential for the region is very good.

The Biwabik Iron-Formation flanks the south side of the Giants Range and extends southwestward beyond Grand Rapids. Perme able parts of this formation can support large withdrawals of ground- water. Calumet, Cooley, Keewatin, Marble, Nashwauk, and Taconite obtain their water from the iron-formation.

Ice-Contact stratified drift and outwash aquifers aro widespread throughout the region. Bovey and Coleraine obtain their water from stratified drift, and Grand Rapids obtains its water from drift and the Biwabik Iron-Formation. The ground-water potential of the region is good.


TOIMI DRUMLIN FIELD

The Toimi drumlin field is a belt of south westward-trending clrum- lins extending from the east end of the Giant Kange (pi. 1). These ridgeS control the drainage within the region, and the valleys between them tire occupied by lakes, streams, and swamps. The ridges that were examined in the field were composed of a gray to brown bouldery till.

The Dunka Kiver drains the region north of the Laurentian Divide. The St. Louis River and its tributaries, which include the Partridge and Whitef ace Rivers, drain the region to the southwest. Th°, region contains several lakes and the Whiteface reservoir. The surface- water potential of the region is fair.

Some ground water can be obtained from isolated deposits of ice- contact stratified drift, which are scattered throughout the region. The Biwabik Iron-Formation flanks the south side of the Giants Range in this region, but it is mainly dense taconite here and not a gooi source of ground water. The ground-water potential of the region is poor.

QUALITY OF WATER

In selecting a source of water, quality is an important consideration. Quality requirements vary widely depending on the particular use for which the water is intended. Although water is commonly treated to make it acceptable for the intended use, the cost of this treatment de pends on the quality of the "raw" water. In many areas alternative sources are available, and quality is the determining factor in the final selection of a supply.

Records on the chemical quality of surface water in the Mesabi and Vermilion Iron Ranges have been obtained since 1955. The records include daily observations for several years at 4 stream sites Embarrass River at Embarrass, Second Creek near Aurora, Partridge River near Aurora, and West Two River near Iron Junction; monthly or semiannual observations for several years at 13 other stream sites; and single observations for numerous lakes. Records of the chemical quality of ground water were obtained about 1957, mostly for municipal supplies or for test holes in the vicinity of municipalities.

Chemical analyses by the U.S. Geological Survey were made by using methods described by Rainwater and Thatcher (1960). Ana lytical results are given mostly in parts per million, which is a unit weight of a constituent in a million unit weights of water. Specific conductance is given in micromhos per centimeter at 25°C; this is a measure of the capacity of the water to conduct an electrical current and is closely related to the dissolved-solids content (residue on


evaporation at 180°C) of the water. The degree of acidity or alkalinity is indicated in pH units, which are the negative logarithms of the hydrogen ion concentration in moles per liter. Color is given in units of the platinum-cobalt scale (Hazen, 1892).

CBITEBIA FOB EVALUATING THE QUALITY OF WATEB

The quality of water for municipal use can be evaluated by compar ing the chemical characteristics of the water with the drinking-water standards of the U.S. Public Health Service (1962), given in part below:

MaximumConstituent or property concentration Iron (Fe)_______________________________ppm__ 0.3 Manganese (Mn) ___________________________do__ . 05 Sulfate (SO*) _____________________________do__ 250 Chloride (Cl) ______________________________do__ 250 Fluoride (F)_______________________________do__ *0. 8-1. 7 Nitrate (NOi) _____________________________do__ 45 Dissolved solids____________________________do__ 500 Color ____________________________________urits_ 15 Turbidity ________________________________do__ 5

1 Varies depending on annual average of maximum daily air temperat-re.

The significance of the chemical constituents or properties of drink ing water is described in detail by Welsh and Thomas (1960). The significance of these and other constituents in relation to industry and irrigation is described by Lohr and Love (1954), the U.S. Salinity Laboratory Staff (1954), and Hem (1959).

No specific standards for hardness have been established, but the following ratings, recognized by the U.S. Geological Survey, are used in this report.

Hardness (ppm)

0-60_.____

61-120 __ . 121-180 __

181+ __ __

Eating

Soft_____ .._ __._.

Moderately hard____ Hard________ ______

Very hard__________

Suitability

Suitable for many uses vithout furthersoftening.

Usable except in some industrial applications. Softening required by laundries and some

other industries. Requires softening for many uses.

No generally accepted standards for silica have been established, although maximum concentrations have been recommended for cer tain industrial applications. For this report and for closely related reports (Cotter and others, 1965, a, b, c, d, and e), water having more than 20 ppm is considered to be siliceous and 10-20 ppm is moderately siliceous.


GROUND WATER

The chemical composition of ground water from municipal wells shows an average dissolved-solids content of about 230 ppm (table 7). The principal constituents of well waters are calcium, magnesium, and bicarbonate. Sulfate is present in significant concentrations in most well waters. The water generally is moderately siliceous, is hard or very hard, and contains much iron and manganese. Other dissolved constituents, such as sodium, potassium, chloride, fluoride, nitrate, and boron, occur in such low concentrations that thQy have little effect on the use of the water. The color of water from most wells is 5 units or less and for some is nearly zero. The turbidity in water from most wells is less than 2 units, but for a few it is between 20 and 30.

TABLE 7. Chemical composition of untreated ground water used for municipalsupply (1960)

[Results in parts per million except as indicated]

Constituent or property

Silica (SiOj) -. . .Iron (Fe) ___ ____________

Calcium (Ca).... __________

Sodium (Na) ___ . ................

Sulfate (SO4) . . ___________Chloride (Cl)___ ....................Fluoride (F)_______.._.._.__.....____Nitrate (NOs) .... __ . ___ - ___

Specific conductance (micromhos at 25° C.).. ................... .......

pH...................... ............

Glacial drift (24 wells)

Maxi mum

33 10 5.5

90 48 9.1 3.3

413 88 12

.3 1.6 .11

477 420

339

758 7.8

130 49

Mini- mum

13 .04 .00

20 8.9 2.5 .6

102 3.8 .0 .0 .0 .00

127 87

84

178 6.5 0

42

Aver age

21 1.9 .83

52 19 5.8 1.8

220 34 3.5 .2 .5 .04

253 212 32

180 6

408 7.4

10 45

Per cent 1

9.0 .9 .3

20.3 7.7 2.4 .7

43.5 13.4 1.5 .1 .2 .0

Biwabik Iron-Formation (15 wells)

Maxi mum

26 4.9 1.8

76 36 12 5.8

333 88 12

.2 7.1 .09

396 339

273

648 7.8 5

50

Mini mum

4.1.05 .00

18 6.6 4.1 .9

94 2.0 .0 .0 .0 .01

104 72

77

162 6.8 0

43

Aver age

14 .82 .35

45 18 7.1 2,1

219 23 3,0 .1 .9 .06

213 191

11 180

8

3727.4 2

45

Per cent 1

6.4 .4 .2

20.6 8.2 3.3 1.0

48.6 10.1 1.1 .0 .2 .0

1 By weight of dissolved solids.

Most of the wells for which chemical analyses of water were made produce water from drift or from the Biwabik Iron-Formation. Dif ferences in most chemical characteristics of water from the drift and from the Biwabik are relatively slight (table 7). On the average, water from the Biwabik has a slightly lower dissolved-solids content and much lower silica, iron, and manganese content than water from the drift. Water from the drift is more likely to have significant amounts of sulfate and is more likely to be colored. The average of 10 units of color for water from the drift, however, may be misleading


because the analysis of water from one municipal supply showed 130 units, which significantly affected the average. Had this high result been omitted, the average would have been only four units.

For most chemical characteristics, water from the drift and water from the Biwabik have similar percentages by weight and similar maximums and minimums of dissolved solids as shorn in table 7. The similarity in water from the two types of deposits results partly because much of the water in the Biwabik was previously in contact with the overlying drift. In some parts of the Biwabik, most of the soluble mineral matter was leached when the ore bodies were being formed; consequently, after percolating into the Biwabik, the water changes little in chemical composition.

Much of the drift contains a relatively large number of limestone and shale fragments that are sources of the calcium and bicarbonate in the ground water.

Complex iron silicates, iron oxides, carbonates, and quartz are the predominant minerals in the rocks of the Biwabik Iron-Formation. Several of these minerals contribute calcium and bicarbonate to the water. Gruner (1946, p. 21) reported that calcite, calcium car bonate, is recognizable with the unaided eye in drill cc ves in the top 10-20 feet of the Biwabik in the eastern half of the rr.nge, and that it may be observed microscopically as well-formed white or colorless rhombohedrons in many samples from all parts of the formation. He also reported amphiboles and pyroxenes, complex silicates containing calcium, in the eastern Mesabi Eange. White (1954, p. 24 and 29) indicated that the lower cherty member of the Biwabil* contains cal cite, that limestone beds occur at the contact of the Biwabik and the Virginia, and that the limestone in both the Biwabik and the Vir ginia is continuous along nearly all of the main Mesabi Range.

SURFACE WATER

Records of water quality indicate that the dissolved-solids content is less than 200 ppm (parts per million) and averages less than 100 ppm for most streams in the Mesabi and Vermilion Ranges. Like the ground water, the surface water contains principally calcium, mag nesium, and bicarbonate. Iron is present in concentrations from a few tenths to about 1 ppm, manganese is generally absent, and the water is relatively soft.

The only surface water that is being used for municipal supply is from lakes. The dissolved-solids content of the water from the four lakes (Burntside, Colby, Elby, and St. Marys) was less than 100 ppm, and the average hardness of the water was 46 ppir. Except for Colby Lake, the water had little silica or iron and was only slightly


colored. The chemical quality of the water undoubtedly varies some what with changes in lake altitudes.

The frequency distributions in table 8 provide an estimate of the ranges in concentration of chemical constituents likely to be present in streamflow, and they provide a convenient means for comparing the quality of the water from one stream to another. Data in the table indicate, for example, that dissolved solids did not exceed 100 ppm in water from Bear Island and South Kawishiwi Rivers, where as it did exceed 100 ppm in a significant percentage of samples from all other streams. Also, the dissolved-solids content in wate1* from East Two River and Swan River is generally much higher than that from other streams. Water from most of the streams is colored. All samples from five of the streams indicate that the water is soft.

PRESENT WATER DEVELOPMENT

The quantity of available water leaving the area shown in figure 1 has been estimated at 700 bgy (billion gallons a year). This esti mate is based on available surface-water data and a precipitation of 27 inches for the water year 1959 (October 1958-September 1959). Sur face water entering the area was subtracted from outflow, and ground water entering the area by subsurface flow has not been included in the total. This TOO bgy is about 26 percent of the precipitation. A part of the flow of surface streams is from ground water that dis charges to the stream as seeps and springs. During periods of little precipitation almost all the surface flow of a stream is from ground- water discharge. Using the minimum streamflow for the year as the increment of flow from ground water, at least 200 bgy, or abont one- third of the annual surface-water flow, is contributed from ground water. This is equal to a flow of about 400,000 gpm (gallons per minute). In addition to this, a large quantity of water leaves the area as ground-water underflow.

Major industrial and municipal water users on the Mesabi and Vermilion Iron Ranges utilize about 135 bgy. Only about 5 percent of this water is "consumed" or is not available for reuse within the area.

INDUSTBIAL USE

The largest single water user in the area is the largest industry, mining. Although the "shovel" ores of the Mesabi and the "lump grade" ores of the Vermilion are "direct shipping" and require no beneficiation, the lower grade ores must be concentrated. The latter are the magnetic taconite ores and the "wash" ores. Most of the water used to process these ores is surface water from lakes, rivers, and manmade catchment basins.

GO

O

TABL

E 8.

Fre

quen

cy d

istr

ibut

ion

of

chem

ical

con

stit

uent

s an

d pr

oper

ties

of

wat

er f

rom

str

eam

s

[Res

ults

are

give

n in

par

ts p

er m

illio

n ex

cept

as i

ndic

ated

]

Sta

tion

5-1

265

5-1

31

0

5-1

260 .

4-0

19

5

4-0

18

9

4-01

87.7

.---

4

-01

70

4-0

18

0

5-1

28

5

4-01

65

5-1

25

0

5

-12

55

.

5-1

305

4-0

20

0 .

4-0

19

0

Str

eam

sit

e

Wes

t T

wo

Riv

er n

ear

Iron

Jun

ctio

n _

__

__

Per

iod

of

reco

rd

1955

-62

1955

-61

1955

-60

1955

-60

1957

-30

1959

-60

1955

-62

1955

-60

1955

-59

1955

-60

1955

-59

1957

-59

1955

-60

1955

-60

1955

-60

1955

-60

1956

-57

Sil

ica

(SiO

a)Ir

on

(Fe)

Man

gane

se

(Mn)

Cal

cium

(C

a)M

agn

esiu

m

(Mg)

Sod

ium

(N

a)P

otas

sium

(K

)

02

Bic

arbo

nate

_.

(H

C0

3)

§

Per

cent

age

of s

ampl

es i

n w

hich

con

cent

rati

ons

exce

eded

^ M

10

0 25

56

38

11 50

67

38

49

33 14

77 0 20

26 41 27

20

0 0 0 0 0 0 2 0 0 0 0 8 0 0 0 0 0

0.3 40

10

0 10

0 62 0 0 81

32

45

100

100 29

62

78

95 38

20

1.0 0 12

22

0 0 0 19 0 3 22 0 0 0 0 5 0 0

0.05 0 17

14

29

20 33 0 11

0 0 0 17

14

20 25 0

0.3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20

0 0 0 50

100 75

3 4 7 0 55 0 0 0 77

57

40

0 0 0 0 46 0 0 0 0 0 0 0 0 0 0 23 3

10

0 0 0 38

93 67 0 0 2 0 0 52 0 0 0 60

37

20

0 0 0 0 43 0 0 0 0 0 0 3 0 0 0 10 1

10

0 0 0 12

83 17 0 0 1 0 0 11 0 0 0 37 3

20

0 0 0 0 7 0 0 0 0 0 0 0 0 0 0 0 0

1

0 43

25

71

100

100 24

57

53

0 47

92 0 11

61 93

94

2

0 0 0 29

93 67 2 0 13 0 2 45 0 0 3 50

30

50

0 0 0 87

100

100 34

71

41 0 42

88 0 0 38 97

91

,

. .

UA

100

§ i i

AND

VERMILION IRON

RAN

C000£S§

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°° CT8°°°

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4.4.34.2

A32 WATER KESOURCES OF MESABI AND VERMILION IRON RANGES

The Erie Mining Co. plant at Hoyt Lakes and tl 3 Oliver Iron Mining Division plant at Mountain Iron have an average use of more than 6,000 gallons of water per ton of taconite concentrate. Of this, nearly 700 gallons is not available for reuse. This âter is either lost in ponding, evaporated, or contained in the final product.

Data from 13 "wash" ore plants show an average UTB of 1,200 gal lons of water per ton of concentrate of which about 125 gallons is not available for reuse.

In 1961, 7.6 million tons of taconite concentrate were shipped. Of the nearly 50 billion gallons of water used in processing, more than 5 billion gallons were not available for reuse. The same year, 16.7 million tons of "wash" ore concentrate were shipped from both iron ranges. Based on averages from the 13 plants, about 20 billion gal lons of water were used in processing, of which about 2 billion gallons were not available for reuse.

Two steam-powered electric generator plants owned by the Minne sota Power and Light Co. use large volumes of water. The plant near Cohassett used 3 million gallons of ground water and 17.4 bil lion gallons of surface water in 1959, and their plant near Hoyt Lakes used 1 million gallons of ground water and 45.5 billion gallons of surface water during the same year. Very little water used in either plant is consumed.

The Blandin Paper Co. at Grand Eapids uses about 1.3 billion gal lons of surface water per year (1957) in wood processing. Other minor industrial water uses include gravel washing operations, dairies, and wood and vegetable processing. Many of the open-pit mines on the Mesabi Range have wells for drinking and sanitation water.

MUNICIPAL USE

About two-thirds of the population within the area si own on plate 1 is concentrated in 26 municipalities, of which 4 use surface water (lakes) and 22 use ground water for municipal supplies. Virginia obtains most of its water by pumping a flooded mire shaft at the bottom of an open-pit mine. Although drifts run from the shaft beneath a lake in the pit bottom, most of the water is from the Biwabik Iron-Formation. Of the 22 municipal ground-water supplies, 8 are from drift, 8 from the Biwabik Iron-Formation, 2 froir a combination of these aquifers, 2 from the Biwabik Iron-Formation and the Vir ginia Argillite, 1 from the 3 aquifers, and 1 from the Virginia Argillite, above.

Treatment facilities are varied. Ten municipalities using ground water do not treat their supplies. The surface-water sources all in clude prechlorination, coagulation, sedimentation, filtration, and post- chlormation. Of the municipalities that do treat grcund water, six


either aerate and filter the water to remove iron, or hold the iron in solution by polyphosphate stabilization, or both. Kinney has a se rious manganese problem and uses coke and pyrolusite beds to remove it. Babbitt, Chisholm, and Virginia have more complete treatment facilities including coagulation, chlorination, and nitration.

The total water consumption of the 26 municipalities is about 8 million gpd (gallons per day) or 2.8 bgy. This is an average per capital consumption of about 92 gpd.

CONSIDERATIONS FOR FUTURE DEVELOPMENT

Obviously, it would not be desirable or economical to capture and utilize all the water moving through the area. Where maximum de velopment of the water resources is required, streamflow can be used during periods of sustained high flow and lakes and ground water used during periods of sustained low flow. Aquifers and lakes are storage reservoirs, and can supply water during the fall and winter, during periods of low streamflow.

When heavily pumped, the water level in an aquifer lowers as the aquifer is emptied. During spring and summer rains, the aquifer is refilled. The periodic lowering of the water table is beneficial as it reduces the evapotranspiration losses.

Water stored in lakes and in the surrounding shallow aquifers can be obtained from either source. Lowering the water table near the edge of a lake by pumping a well induces water to flow from the lake to the well. As the lake level is lowered the entire lake basin func tions as a tremendous well, inducing ground-water inflow fôm the surrounding area. Water induced to flow from a lake to ir well is commonly of better quality than lake water; specifically, it is less turbid and more uniform in temperature.

In all areas the total supply is limited first by the total precipita tion falling in the area and second by the quantity available from storage during prolonged periods of no precipitation. Other things being equal, the area with the largest surface- or ground-water reser voirs will yield the greatest quantity of water. Economical utiliza tion of ground water requires that wells be completed in p3rmeable deposits so that each well can draw large quantities of water from an extensive aquifer. Because physiography controls the distribution of the water resources in the Mesabi and Vermilion Iron Eanges, the physiography of the region in which the water occurs must be con sidered in order to achieve optimum development.

The best surface-water potential is in the Border-Lakes region and Morainal and Ice-Contact region, and the best ground-water potential is in the Ice-Contact region and the Morainal and Ice-Contact region.


In order to provide more detailed information for future water use and management, a series of reports has been prepared. These re ports (Cotter and others, 1965a, b, e, d, and e) contain descriptions of the hydrology in the vicinity of 26 municipalities, 22 of which obtain their water supplies from the 3 previously mentioned regions. Also of assistance is the surficial geologic map (Cotter, Young, and Winter, 1964) that outlines glacial landforms indicating the presence of po tential aquifers in most of the report area.

The water quality at a potential site must be considered. The dissolved-solids content of the ground water averages about 220 ppm, and that of most streams averages less than 100 ppm. Both ground and surface waters contain principally calcium, magnesium, and bi carbonate and generally contain high concentrations of iron. Most of the ground water also contains high concentrations of manganese and is hard or very hard. Most of the surface water is highly colored, but it is soft or only moderately hard. Generally the grouc d water is of good quality for most uses if it is softened and if it is treated to remove iron and manganese, and surface water is of good quality for most uses if it is treated to remove color and iron.

LITERATURE CITED

Bergquist, H. R., 1944, Cretaceous of the Mesabi Iron Range, Minnesota: Jour. Paleontology, v. 18, no. 1, p. 1-30.

Clements, J. M., 1903, The Vermilion iron-bearing district of Minnesota: U.S. Geol. Survey Mon. 45, 463 p.

Cotter, R. D., and Rogers, J. E., 1961, Exploratory drilling for g-ound water in the Mountain Iron-Virginia area, St. Louis County, Minnesota: U.S. Geol. Survey Water-Supply Paper 1539-A, 13 p.

Cotter, R. D., and Young, H. L., 1960, Municipal water supplies on the Mesabi and Vermilion Iron Ranges, northeastern Minnesota: Minnesota Iron Range Resources and Rehabilitation Commission Basic Data Release 1, 61 p.

Cotter, R. D., Young, H. L., Petri, L. R., and Prior, C. H., 1965a, Water resources in the vicinity of municipalities on the western Mesabi Iron Range, north eastern Minnesota: U.S. Geol. Survey Water-Supply Paper 1757-B.

1965b, Water resources in the vicinity -of municipalities on the west- central Mesabi Iron Range, northeastern Minnesota: U.S. Geol. Survey Water-Supply Paper 1759-C.

1965c, Water resources in the vicinity of municipalities on the central Mesabi Iron Range, northeastern Minnesota: U.S. Geol. Survey Water-Sup ply Paper 1759-D.

1965d, Water resources in the vicinity of municipalities on the east- central Mesabi Iron Range, northeastern Minnesota: U.S. Geol. Survey Water-Supply Paper 1759-E.

1965e, Water resources in the vicinity of municipalities on the easternMesabi Iron Range and the Vermilion Iron Range, northeastern Minnesota: U.S. Geol. Survey Water-Supply Paper 1759-F.

Cotter, R. D., Young, H. L., and Winter, T. C., 1964, Preliminary surflcial geo logic map of the Mesabi-Vermilion Iron Range area, northeastern Minnesota : U.S. Geol. Survey Misc. Geol. Inv. Map 1-403.


Dalrymple, Tate, 1960, Flood-frequency analysis: U.S. Geol. Survey Water-Sup ply Paper 1543-A, 80 p.

Ferris, J. G., Knowles, D. B., Brown, R. H., and Stallman, R. W., 1962, Theoryof aquifer tests: U.S. Geol. Survey Water-Supply Paper 1536-E, 174 p.

Flint, R. F., 1957, Glacial and Pleistocene geology: New York, John îley &Sons, 553 p.

Goldich, S. S., Nier, A. O., Baadsgaard, Halfdan, Hoffman, J. H., and Krueger,H. W., 1961, The Precambrian geology and geochronology of Minnesota:Minnesota Geol. Survey Bull. 41,193 p.

Grout, F. F., and Broderick, T. M., 1919, The magnetite deposits of the easternMesabi Range, Minnesota: Minnesota GeoL Survey Bull. 17,58 p.

Gruner, J. W., 1941, Structural geology of the Knife Lake area of northeasternMinnesota: Geol. Soc. America Bull., v. 52, no. 10, p. 1577-1642.

1946, The mineralogy and geology of the taconites and iron ore? of the Mesabi Range, Minnesota: St. Paul, Office of the Commissioner of the Iron Range Resources and Rehabilitation, 127 p.

1956, The Mesabi Range, in Preeambrian of northeastern Minnesota:Geol. Soc. America Guidebook Ser., Minneapolis Mtg., p. 182-215.

Hazen, Alien, 1892, A new color standard for natural waters: American Chem.Jour., v. 12., p. 427-428.

Hem, J. D., 1959, Study and interpretation of the chemical characteristics ofnatural water: U.S. Geol. Survey Water-Supply Paper 1473, 269 p.

Leith, C. K., 1903, The Mesabi iron-bearing district of Minnesota: U.S. Geol.Survey Mon. 43,316 p.

Leith, C. K., Lund, R. J., and Leith, Andrew, 1935, Pre-Gambrian rocks of theLake Superior region; a review of newly discovered geologic features witha revised geologic map: U.S. Geol. Survey Prof. Paper 184,34 p.

Leverett, Frank, 1932, Quaternary geology of Minnesota and parts of adjacentstates: U.S. Geol. Survey Prof. Paper 161,149 p.

Lohr, E. W., and Love, S. K., 1954, The industrial utility of public water suppliesin the United States, 1952, part 2, States west of the Mississippi River: U.S.Geol. Survey Water-Supply Paper 1300,462 p.

Martin, Lawrence, 1911, The Pleistocene, chapter 16, in Van Hise, C. R., andLeith, C. K., The geology of the Lake Superior region: U.S. Geol. Surrey Mon.52, p. 427-459.

Meinzer, O. E., 1923a, The occurrence of ground water in the United States: U.S.Geol. Survey Water-Supply Paper 489, 321 p.

1923b, Outline of ground-water hydrology with definitions: U.S. Geol.Survey Water-Supply Paper 494,71 p.

Minnesota Department of Conservation, 1951, Surface water supplies of theMesabi Iron Range: Minnesota Div. of Waters Bull. 5,117 p.

Parker, G. G., Ferguson, G. E., Love, S. K., and others, 1955, Water resourcesof southeastern Florida: U.S. Geol. Survey Water-Supply Paper 1255 965 p.

Prior, C. H., and Hess, J. H., 1961, Floods in Minnesota magnitude and frequency :Minnesota Div. of Waters Bull. 12,142 p.

Rainwater, F. H., and Thatcher, L. L., 1960, Methods for collection and analysisof water samples: U.S. Geol. Survey Water-Supply Paper 1454,301 p.

Reid, I. L., 1956, The Vermilion Range, in Precambrian of northeastern Minne sota : Geol. Soc. America Guidebook Ser., Minneapolis Mtg., p. 109-110,

Schwartz, G. M., Ed., 1956, Precambrian of northeastern Minnesota: Geol. Soc.America Guidebook Ser. Minneapolis Mtg., 235 p.

Stauffer, C. R., and Thiel, G. A., 1933, The limestones and marls of Minnesota,Minnesota Geol. Survey Bull. 23.


Thiel, G. A., 1947, The geology and underground waters of northeastern Minne sota : Minnesota Geol. Survey Bull. 32,247 p.

Thwaites, F. T., 1950, Outline of glacial geology: Ann Arbor, Edwards Bros.,Inc., 129 p.

U.S. Bureau of the Census, 1956, U.S. Census of agriculture, 1954, v. 1, Countiesand state economic areas, Part 8: Washington, U.S. Govt. Printing Office,246 p.

U.S. Department of Agriculture, 1941, Climate and man, yearbook of agriculture,1941: Washington, U.S. Govt. Printing Office, 1248 p.

U.S. Geological Survey, 1961, Surface water supply of the United States, 1960,part 4, St. Lawrence River basin: U.S. Geol. Survey Water-Supply Paper1707, 437 p.

1962a, Surface water supply of the United States, 1960, part 5, Hudson Bay and upper Mississippi River basins: U.S. Geol. Survey Water-Supply Paper 1708, 588 p.

1962b, Surface water records of Minnesota, 1961: Washirston, U.S. Govt.Printing Office, 174 p.

U.S. Public Health Service, 1962, Drinking water standards, 1962: U.S. PublicHealth Service Pub. 956, Washington, U.S. Govt. Printing Office, 61 p.

U.S. Salinity Laboratory Staff, 1954, Diagnosis and improvement of saline andalkali soils: U.S. Dept. Agriculture, Agriculture Handb. 60,160 p.

Van Hise, C. R., and Leith, C. K., 1911, The geology of the Lake Superior region:U.S. Geol. Survey Mon. 52, 641 p.

Welsh, G. B., and Thomas, J. F., I960, Significance of chemical I'-nits in USPHSdrinking water standards: Am. Water Works Assoc. Jour., v. 52, no. 3, p.289-300.

White, D. A., 1954, The stratigraphy and structure of the Mesali Range, Minne sota : Minnesota Geol. Survey Bull. 38, 92 p.

Wright, H. E., 1955, Valders Drift in Minnesota: Jour. Geology, v. 63, no. 5, p.403-411.

1956, Landforms and glacial history of northeastern Minnesota, in Pre-cambrian of northeastern Minnesota: Geol. Soc. America Guidebook Ser.,Minneapolis Mtg., p. 10-19.

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